Disazo dyes



United States Patent 3,092,616 DISAZO DYES Ermanno Gaetani, Milan,Italy, assignor to Aziende Colori Nazionali Afiini Acna S.p.A., Milan,Italy, a corporation of Italy No Drawing. Filed Apr. 14, 1960, Ser. No.22,126

Claims priority, application Italy Dec. 15, 1959 3 Claims. (Cl. 260-486)An object of the present invention is to provide certain new waterinsoluble disazo dyes of the general Formula A The compounds comprisedin general Formula A, are obtained by coupling one mol of an amino azocompound of the type:

wherein R, R and R have the above mentioned meaning, R is hydrogen, withone mol of a compound of the type:

The following examples will further illustrate my invention howeverwithout limiting its scope. (All parts are by weight unless otherwiseindicated.)

Example 1 25.6 g. 4-amino-2-methyl-4'-nitroazobenzene are diazotised in250 g. water, 30 g. dimethylformamide and 40 g. hydrochloric acidsolution (density 1.17) by the addition of 7 g. NaNO in 20 g. water andkeeping the temperature at about 10-15" C. The diazo-azo compoundobtained is introduced into a solution of 14.5 g. N,N-dimethyl-metatoluidine in 200 g. water and g. hydrochloric acid solution; afteraddition of the diazo compound, a 50% aqueous sodium acetate solution isgradually added until the mass does not present any acid reaction with aCongo red indicator.

The disazoic dye obtained is filtered, washed and c1 c1 I I I OH3,092,616 Patented June 4, 1963 ice dried; it consists of a brownish-redpowder (melting point 240 C.) having the formula:

CH3 CH3 I OH I NOON=NGN=NGR/ \CH By paper chromatography it gives auniform red spot which turns to violet with hydrochloric acid andremains unaltered with sodium hydroxide. Example 2 26.6 g.4-amino-2,3-dichloro-azobenzene are diazotised as usual in 300 g. waterand 35 g. HCl (sp. gr. 1.17) by addition of a solution of 7 g. NaNO in20 g. water and keeping the temperature at about 10 to 15 C. Thediazo-azo compound obtained is coupled with a solution of 14.5 g.N,N-dimethyl-meta toluidine as described in Example 1. The .disazo dyeobtained is a brownish-red powder with a melting point of 148 C., havingthe formula:

01 Cl CH3 om By paper chromatography it gives a violet-red spot whichdoes not turn with acids or alkalies.

Example 3 27.9 g. 4-amino 2 methyl-3-trifluoro-methyl-azobenzene arediazotised as usual and the diazo-azo compound obtained is coupled witha solution of 14.5 g. N,N- dimethyl-meta-toluidine operating asdescribed in Example 1. The disazo dye obtained, having the formula:

or, 0H, on,

C H; and

CH3 2. A disazo dye, insoluble in water, having the formula:

CH3 CH3 I /oH,

3. A disazo dye, insoluble in water, having the formula:

CH: References Cited in the file of this patent UNITED STATES PATENTS

1. A DISAZO DYE, INSOLUBLE IN WATER, SELECTED FROM THE GROUP CONSISTINGOF DYES HAVING THE FORMULA: